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Träfflista för sökning "WFRF:(JULIN R) srt2:(2005-2009)"

Sökning: WFRF:(JULIN R) > (2005-2009)

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1.
  • Petts, A., et al. (författare)
  • Lifetime measurements and coulomb excitation of light Hg nuclei
  • 2009
  • Ingår i: Capture Gamma-Ray Spectroscopy and Related Topics. - : American Institute of Physics (AIP). - 9780735406230 ; , s. 414-418
  • Konferensbidrag (refereegranskat)abstract
    • Two complementary experimental programs have taken place to investigate the origin and evolution of shape coexistence in the light mercury region. Recoil Distance Doppler-shift measurements were performed at the University of Jyväskylä utilizing the Köln plunger device in conjunction with the JUROGAM + RITU + GREAT setup. In addition, Coulomb excitation measurements of 184,186,188Hg were performed at REX-ISOLDE using the MINIBALL Ge-detector array. The results of the lifetime measurements of the yrast states up to Iπ = 10+ in 182Hg are reported. Preliminary analysis of the Coulomb excitation data is also discussed.
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2.
  • Petri, M., et al. (författare)
  • Nuclear levels in proton-unbound I-109 : Relative single-particle energies beyond the proton drip line
  • 2007
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 76:5
  • Tidskriftsartikel (refereegranskat)abstract
    • A level scheme has been constructed for the proton-unbound, T-z=3/2 nuclide I-109(53)56 following a recoil-decay-tagging experiment using the Ni-58(Fe-54, p2n gamma) reaction at a beam energy of 195 MeV. The experiment was performed using the highly efficient JUROGAM gamma-ray spectrometer in conjunction with the RITU gas-filled recoil separator and the GREAT focal-plane spectrometer. Cranking calculations are used to interpret band structures built on pi g(7/2) and pi h(11/2) states in a weakly deformed, triaxial nucleus.
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3.
  • Wadsworth, R., et al. (författare)
  • THE NORTHWEST FRONTIER : SPECTROSCOPY OF N similar to Z NUCLEI BELOW MASS 100
  • 2009
  • Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 40:3, s. 611-620
  • Tidskriftsartikel (refereegranskat)abstract
    • The spectroscopy and structure of excited states of N similar to Z nuclei in the mass 70-100 region has been investigated using two techniques. In the A similar to 70-80 region fusion evaporation reactions coupled with the recoil-beta-tagging method have been employed at Jyvaskyla to study low-lying states in odd-odd N = Z nuclei. Results from these and other data for known odd-odd nuclei above mass 60 will be discussed. In the heavier mass 90 region a fragmentation experiment has been performed using the RIS-ING/FRS setup at GSI. This experiment was primarily aimed at searching for spin gap isomers in nuclei around A similar to 96. The objectives of the latter experiment will be discussed.
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4.
  • Grahn, T., et al. (författare)
  • Collectivity and configuration mixing in Pb186,188 and Po194
  • 2006
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 97:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Lifetimes of prolate intruder states in Pb186 and oblate intruder states in Po194 have been determined by employing, for the first time, the recoil-decay tagging technique in recoil distance Doppler-shift lifetime measurements. In addition, lifetime measurements of prolate states in Pb188 up to the 8+ state were carried out using the recoil-gating method. The B(E2) values have been deduced from which deformation parameters |β2|=0.29(5) and |β2|=0.17(3) for the prolate and the oblate bands, respectively, have been extracted. The results also shed new light on the mixing between different shapes.
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5.
  • Herzberg, R-D, et al. (författare)
  • Isomer spectroscopy in No-254
  • 2006
  • Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; T125, s. 73-77
  • Tidskriftsartikel (refereegranskat)abstract
    • Isomeric states in No-254 were investigated using a calorimetric method. Two different isomers were found with half-lives of T-1/2 = 266 +/- 2 ms and T-1/2 = 184 +/- 3 mu s, respectively. The dominant decay path of the 184 mu s isomer proceeds via states feeding the longer-lived 266 ms isomer. The 266 ms isomer in turn decays via a two-quasi-particle K = 3 band to the ground-state band. The full decay path was observed with the GREAT spectrometer located at the focal plane of the gas-filled separator RITU at the Accelerator Laboratory in Jyvskyl. This work sheds light on the two-quasi-particle structure in this transfermium nucleus.
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6.
  • Joss, D. T., et al. (författare)
  • Yrast states and band crossings in the neutron-deficient platinum isotopes Pt169-173
  • 2006
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 74:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The yrast states in the light platinum isotopes Pt169-173 have been investigated in a recoil-decay tagging experiment using the JUROGAM gamma-ray spectrometer in conjunction with the RITU gas-filled recoil separator and the GREAT tagging spectrometer. Gamma-ray transitions have been established for the first time in the odd-N isotopes, Pt-169 and Pt-173, and the yrast sequences in Pt-170 and Pt-172 have been extended. We discuss the possibility that the weakly deformed yrast structures of Pt-170, Pt-172, and Pt-173 are crossed by a deformed intruder configuration at spin similar to 8h.
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7.
  • Joss, D. T., et al. (författare)
  • Yrast structures in the light Pt isotopes Pt169-173
  • 2005
  • Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 31:10, s. S1715-S1718
  • Tidskriftsartikel (refereegranskat)abstract
    • The exploitation of the recoil-decay tagging (RDT) technique has reinvigorated experimental investigations of the shape coexistence phenomenon in heavy neutron-deficient nuclei. In a recent experiment using the JUROGAM and GREAT spectrometers in conjunction with the RITU gas-filled separator, excited states have been investigated in the light platinum isotopes. In addition to extending the yrast sequences in Pt-170 and Pt-172, the first observation of excited states in the odd-N isotopes, Pt-169 and Pt-173, is reported. The bands are discussed in terms of trends in level excitation energies as a function of neutron number.
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8.
  • Kröll, Th, et al. (författare)
  • Quadrupole Collectivity of neutron-rich nuclei around 132Sn
  • 2008
  • Ingår i: Frontiers in Nuclear Structure, Astrophysics, and Reactions, FINUSTAR 2007. - : AIP. - 9780735405325 ; 1012, s. 296-299
  • Konferensbidrag (refereegranskat)abstract
    • We report on the "safe" Coulomb excitation of neutron-rich Cd, Xe, and Ba isotopes in the vicinity of the doubly-magic nucleus 132Sn. The radioactive nuclei have been produced by ISOLDE at CERN and postaccelerated by the REX-ISOLDE facility. The γ-decay of excited states has been detected by the MINIBALL array. The presented preliminary results for the B(E2) values are consistent with expectations from phenomenological systematics and will be compared with theoretical calculations.
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9.
  • Lagergren, Karin, et al. (författare)
  • High-spin states in the proton-unbound nucleus Re-161
  • 2006
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 74:2, s. 024316-
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in Re-161 were populated using the Cd-106(Ni-58, p2n) reaction at a beam energy of 270 MeV, resulting in the first observation of gamma rays emitted from this nucleus. The reaction products were separated from scattered beam and fission fragments by the gas-filled recoil separator RITU, and were implanted in the double-sided silicon strip detectors of the GREAT spectrometer. Prompt gamma rays were detected by the JUROGAM Ge detector array and were assigned to Re-161 based on alpha- and proton-decay tagging of the implanted reaction products. The near-yrast high-spin level structure, which was delineated to spins around 39/2, is discussed in the context of the total Routhian surface formalism. The level scheme is interpreted in terms of the alignment of h(9/2)/f(7/2) neutrons at lower spins, followed by excitations involving the pi h(11/2) subshell at higher spins.
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10.
  • Mach, H., et al. (författare)
  • Application of ultra-fast timing techniques to the study of exotic and weakly produced nuclei
  • 2005
  • Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 31:10, s. S1421-S1426
  • Tidskriftsartikel (refereegranskat)abstract
    • Ultra-fast time-delayed techniques have been recently applied in a number of studies where exotic nuclei were identified using advanced selection techniques. These include large Compton-suppressed Ge arrays, in-flight separators or recoil separators. Some of the new results are discussed in this presentation. Besides the results for Mg-32 and Pd-96, they include the first determination of the half-life of the 8(+) state in Ge-80, T-1/2 = 2.95(6) ns, and significantly more precise results for Mn-51 (3680 keV level) and V-48 (421 keV level), T-1/2 = 1760(40) ps and T-1/2.
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11.
  • Page, R. D., et al. (författare)
  • alpha decay of Re-159 and proton emission from Ta-155
  • 2007
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 75:6, s. 061302-
  • Tidskriftsartikel (refereegranskat)abstract
    • The alpha decay of Re-159 has been observed for the first time in reactions of 300 MeV Ni-58 ions with an isotopically enriched Cd-106 target. The Re-159 ions were separated in-flight using the RITU separator and implanted into the GREAT spectrometer. The alpha decay emanates from the proton-emitting pi h(11/2) state in Re-159 with an energy of E-alpha=6776 +/- 26 keV and a branching ratio of 7.5 +/- 3.5%. This alpha decay populates a state in the closed neutron shell nucleus Ta-155, which decays by emitting 1444 +/- 15 keV protons with a half-life of 2.9(-1.1)(+1.5) ms. These values are consistent with the emission of the proton from a pi h(11/2) orbital. These results fit in with the systematics of proton and alpha-particle separation energies in the region, but disagree with the previously reported decay properties of Ta-155.
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12.
  • Page, R. D., et al. (författare)
  • Probing single-particle structures beyond the proton drip line
  • 2007
  • Ingår i: Proton Emitting Nuclei and Related Topics. - : American Institute of Physics (AIP). - 9780735404755 ; , s. 137-142
  • Konferensbidrag (refereegranskat)abstract
    • Single-particle energies have been investigated in the closed neutron shell proton emitter 155Ta. The 155Ta nuclei were populated through the α decay of 159Re, which has been observed for the first time. The 159Re nuclei were produced in reactions of 300 MeV 58Ni ions with an isotopically enriched 106Cd target, separated in-flight using the RITU separator and implanted into the GREAT spectrometer. The 159Re α decay emanates from the proton-emitting πh11/2 state and populates a state in 155Ta which decays by the emission of a proton from a πh 11/2 orbital. The results fit in with the systematics of proton and α-particle separation energies in the region, but disagree with the previously reported decay properties of 155Ta.
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13.
  • Singh, B. S. Nara, et al. (författare)
  • Coulomb shifts and shape changes in the mass 70 region
  • 2007
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 75:6
  • Tidskriftsartikel (refereegranskat)abstract
    • The technique of recoil beta tagging has been developed which allows prompt gamma decays in nuclei from excited states to be correlated with electrons from their subsequent short-lived beta decay. This technique is ideal for studying nuclei very far from stability and improves in sensitivity for very short-lived decays and for high decay Q-values. The method has allowed excited states in Y-78 to be observed for the first time, as well as an extension in the knowledge of T=1 states in Rb-74. From this new information it has been possible to compare Coulomb energy differences (CED) between T=1 states in Br-70/Se-70, Rb-74/Kr-74, and Y-78/Sr-78. The A=70 CED exhibit an anomalous behavior which is inconsistent with all other known CED. This behavior may be accounted for qualitatively in terms of small variations in the Coulomb energy arising from shape changes.
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14.
  • Singh, B. S. Nara, et al. (författare)
  • Recoil Beta Tagging : Application to the study of odd-odd near proton drip line nuclei, Rb-74 and Y-78
  • 2007
  • Ingår i: The European Physical Journal Special Topics. - : Springer Science and Business Media LLC. - 1951-6355 .- 1951-6401. ; 150, s. 147-148
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a study of low-spin states in Rb-74 and Y-78 using the new technique of Recoil Beta Tagging. This yielded new information on Rb-74 and has provided the first evidence for non-isomeric T = 1 states in Y-78.
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15.
  • Wiseman, D. R., et al. (författare)
  • In-beam gamma-ray spectroscopy of Po-190,Po-197
  • 2007
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 34:3, s. 275-281
  • Tidskriftsartikel (refereegranskat)abstract
    • gamma-ray transitions in the neutron-deficient nuclei Po-190,Po-197 have been identified using the JUROGAM Ge detector array coupled to the RITU gas-filled separator and the GREAT spectrometer. The yrast band of Po-190 has been firmly established through gamma-gamma coincidences and extended up to a spin and parity of 14(+). It displays similar behaviour to its isotones Hg-186 and Pb-188 above the 4(+) level, thus confirming its prolate nature. In Po-197 the band built upon the 13/2(+) isomer has been extended up to a spin and parity of 33/2(+), while the non-yrast band has been observed for the first time. The behaviour of Po-197 is found to be similar to that of the nearby even-mass isotopes, which is consistent with the model in which the i(13/2) neutron is weakly coupled to the states in the even-even core.
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16.
  • Wiseman, D. R., et al. (författare)
  • Probe of triple shape coexistence in neutron deficient polonium nuclei
  • 2006
  • Ingår i: AIP Conf. Proc.. - : AIP. - 0735403236 - 9780735403239 ; , s. 560-562
  • Konferensbidrag (refereegranskat)abstract
    • γ-ray transitions in the neutron deficient 190,197Po nuclei have been identified. The yrast band of 190Po has been extended up to a spin and parity of 14+ and is found to display similar systematic behaviour to isotones 186Hg and 188Pb above the 4+ level, thus confirming its prolate nature. In 197Po the band built upon the 13/2+ isomer has been extended up to a spin and parity of 33/2+, while the non-yrast side-band has been observed for the first time. The behaviour of 197Po is found to be similar to that of the nearby even-mass isotopes, which is consistent with the model in which the i13/2 neutron is weakly coupled to the states in the even-even core.
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17.
  • Caballero, L., et al. (författare)
  • Two-phonon octupole excitation in 146Gd
  • 2006
  • Ingår i: AIP Conf. Proc.. - : AIP. - 0735403236 - 9780735403239 ; , s. 213-216
  • Konferensbidrag (refereegranskat)abstract
    • The excited states in 146Gd have been re-investigated with the 144Sm(α,2n) reaction using a modern Ge γ-ray array including a polarimeter. Amongst the non-yrast states populated in this reaction we have identified the aligned 6 + member of the two-phonon octupole quartet from the observation of the E3 branching to the one phonon 3 - state. Our results represent the first observation of a 6 +→ 3 -→0 + E3 cascade in an even-even nucleus.
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18.
  • Hadinia, Baharak, et al. (författare)
  • First identification of gamma-rays in Te-106 using recoil decay tagging technique
  • 2006
  • Ingår i: Frontiers in Nuclear Structure Astrophysics, and Reactions: FINUSTAR. - MELVILLE, NY : AMER INST PHYSICS. - 0735403236 - 9780735403239 ; , s. 457-459
  • Konferensbidrag (refereegranskat)abstract
    • Gamma-ray transitions from excited states in Te-106 have been identified using the recoil decay tagging technique. The experiment which was the reaction Fe-54(Fe-54,2n)Te-106* was performed at the JYFL accelerator facility at the University of Jyvaskyla, Finland. The production cross section was estimated at 25 nb, a new limit for in-beam gamma-ray spectroscopy. A tentative level structure for the ground state band of Te-106 is proposed.
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19.
  • Hadinia, Baharak, et al. (författare)
  • Identification of gamma rays from Au-172 and alpha decays of Au-172, Ir-168, and Re-164
  • 2009
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 80:6, s. 064310-
  • Tidskriftsartikel (refereegranskat)abstract
    • The very neutron deficient odd-odd nucleus Au-172 was studied in reactions of 342 and 348 MeV Kr-78 beams with an isotopically enriched Ru-96 target. The alpha decays previously reported for Au-172 were confirmed and the decay chain extended down to Tm-152 through the discovery of a new alpha-decaying state in Re-164 [E-alpha=5623(10) keV; t(1/2)=864(-110)(+150) ms; b(alpha)=3(1)%]. Fine structure in these alpha decays of Au-172 and Ir-168 were identified. A new alpha-decaying state was also observed and assigned as the ground state in Au-172 [E-alpha=6762(10) keV; t(1/2)=22(-5)(+6) ms]. This decay chain was also correlated down to Tm-152 through previously reported alpha decays. Prompt gamma rays from excited states in Au-172 have been identified using the recoil-decay tagging technique. The partial level scheme constructed for Au-172 indicates that it has an irregular structure. Possible configurations of the alpha-decaying states in Au-172 are discussed in terms of the systematics of nuclei in this region and total Routhian surface calculations.
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20.
  • Hornillos, M. B. G., et al. (författare)
  • gamma-ray spectroscopy approaching the limits of existence of atomic nuclei : A study of the excited states of Pt-168 and Pt-169
  • 2009
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 79:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in the N=90 and N=91 Pt nuclei have been investigated using the JUROGAM and GREAT spectrometers in conjunction with the RITU gas-filled separator. These nuclei were populated via the reactions Mo-92(Kr-78,2n) and Mo-94(Kr-78,3n) at 335 and 348 MeV, respectively. The recoil-decay tagging technique has been used to correlate prompt gamma radiation with the characteristic alpha decays of Pt-168 and Pt-169. A gamma-gamma analysis has allowed a level scheme for Pt-168 to be reported for the first time and the level scheme for Pt-169 to be extended. The excitation energies of the proposed positive-parity yrast states of Pt-168 are compared with calculations based on the interacting boson model and found to be in excellent agreement. These data show a continuation of the trend toward vibrational nuclei as the N=82 shell gap is approached. In addition, new excited states constituting two decay paths have been discovered in Pt-169. .  
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21.
  • Joss, D. T., et al. (författare)
  • Discovery of the proton emitting nucleus 159Re
  • 2007
  • Ingår i: Proton Emitting Nuclei and Related Topics. - : American Institute of Physics (AIP). - 9780735404755 ; , s. 28-33
  • Konferensbidrag (refereegranskat)abstract
    • The observation of the new nuclide 159Re provides important insights into the evolution of single-particle structure in heavy nuclei beyond the proton drip line. The nuclide 159Re was synthesised in the reaction 106Cd(58Ni, p4n) and identified via its proton radioactivity using the RITU gas-filled separator and the GREAT focal-plane spectrometer. Comparisons of the measured proton energy (Ep = 1805±20 keV) and decay half-life (t1/2 = 21±4 μs) with values calculated using the WKB method indicate that the proton is emitted from an h11/2 state. The implications of these results for future experimental investigations into even more proton unbound Re isotopes using in-flight separation techniques are considered.
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22.
  • Joss, D. T., et al. (författare)
  • Probing the limit of nuclear existence : Proton emission from Re-159
  • 2006
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 641:1, s. 34-37
  • Tidskriftsartikel (refereegranskat)abstract
    • The observation of the new nuclide Re-159(75)84 provides important insights into the evolution of single-particle structure and the mass surface in heavy nuclei beyond the proton drip line. This nuclide, 26 neutrons away from the nearest stable rhenium isotope, was synthesised in the reaction Cd-106(Ni-58, p4n) and identified via its proton radioactivity using the RITU gas-filled separator and the GREAT focal-plane spectrometer. Comparisons of the measured proton energy (E-p = 1805 +/- 20 keV) and decay half-life (t(1/2) = 21 +/- 4 mu s) with values calculated using the WKB method indicate that the proton is emitted from an h(11/2) state. The implications of these results for future experimental investigations into even more proton unbound nuclei using in-flight separation techniques are considered.
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23.
  • Ketelhut, S., et al. (författare)
  • gamma-Ray Spectroscopy at the Limits : First Observation of Rotational Bands in Lr-255
  • 2009
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:21, s. 212501-
  • Tidskriftsartikel (refereegranskat)abstract
    • The rotational band structure of Lr-255 has been investigated using advanced in-beam gamma-ray spectroscopic techniques. To date, Lr-255 is the heaviest nucleus to be studied in this manner. One rotational band has been unambiguously observed and strong evidence for a second rotational structure was found. The structures are tentatively assigned to be based on the 1/2(-)[521] and 7/2(-)[514] Nilsson states, consistent with assignments from recently obtained alpha decay data. The experimental rotational band dynamic moment of inertia is used to test self-consistent mean-field calculations using the Skyrme SLy4 interaction and a density-dependent pairing force.
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24.
  • Lieder, E. O., et al. (författare)
  • DSAM Lifetime Studies for Gd-Nd nuclei with EUROBALL and AFRODITE
  • 2008
  • Ingår i: Frontiers in Nuclear Structure, Astrophysics, and Reactions, FINUSTAR 2007. - : AIP. - 1551-7616 .- 0094-243X. - 9780735405325 ; 1012, s. 383-385
  • Konferensbidrag (refereegranskat)abstract
    • Lifetimes of high-spin states have been measured for 142Gd and 134Nd with EU-ROBALL IV and AFRODITE, respectively, using DSAM. From calculations in the cranked Nilsson-Strutinsky model it was concluded that at the high-spin states of the (+,0)1 band, 142Gd represents a triaxial nucleus rotating around the longest principal axis.
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25.
  • O'Donnell, D., et al. (författare)
  • First observation of excited states in Hg-175(95)
  • 2009
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 79:5, s. 051304-
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states of the neutron-deficient nucleus Hg-175, populated using fusion-evaporation reactions, are reported for the first time. The spin and parity of the ground state has been determined to be I-pi=7/2(-) through measurements of the alpha decay to the daughter nucleus Pt-171. A structure based on an isomeric state [T-1/2=0.34(3) mu s] with I-pi=13/2(+) and its decay path to the ground state have been established. The observed structures are interpreted in terms of single-particle configurations, and the trends of coexisting shapes in neighboring nuclei are discussed.
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